The U.S. Department of Energy is accusing Nevada of disregarding national security during its legal battle challenging last year's secret shipment of weapons-grade plutonium by federal officials to a site near Las Vegas.
The department called Nevada's stance "remarkable" in documents filed in federal court in Reno this week.
The documents urged a judge to dismiss Nevada's lawsuit challenging the shipment of the highly radioactive material while a U.S. appellate court considers the state's appeal of an earlier ruling refusing to temporarily ban any future shipments.
Nevada says the Trump administration has acted in bad faith by abusing "top secret" classifications to meet the court-ordered removal of plutonium from South Carolina by the end of this year.
Energy Secretary Rick Perry has said no more plutonium will go to Nevada.
